方法一：

package cn.com.jingdong;import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;public class Main2 {public static void main(String[] args) {Scanner sc = new Scanner(System.in);int n = sc.nextInt();sc.nextLine();String str = sc.nextLine();// 不妨利用数组T(此处用的是list)储存小偷的位置，顺序读取字符串，当读取到X即小偷时，向数组T中记录小偷位置。如：Ti=j表示队列位置j处有一个小偷，该小偷是顺序读取的第i个小偷。List<Integer> list = new ArrayList<Integer>();// 利用数组P记录警察的监视范围，数组P长度和字符串长度相同，初始状态均为0，顺序读取字符串，当遇到数字即警察时，//令：Pjk= 1.....Pj+k= 1表示队列jk到j+k处于监视范围内。j表示警察的位置，k表示警察的监视范围。int[] p = new int[n];for (int i = 0; i < n; i++) {char temp = str.charAt(i);if (temp == 'X') {list.add(i);} else if ('1' <= temp && temp <= '9') {int left = Math.max(0, i - (temp - '0'));int right = Math.min(i + (temp - '0'), n - 1);for (int x = left; x <= right; x++) {p[x] = 1;}}}int count = 0;//如果：PTi= 1表示第i个小偷处于监视范围内。令：count=count+ 1for (int i = 0; i < list.size(); i++) {if (p[list.get(i)] == 1) {count++;}}System.out.println(count);}}

方法二：

package cn.com.jingdong;import java.util.Scanner;public class Main3 {public static void main(String[] args) {Scanner sc = new Scanner(System.in);int n = sc.nextInt();sc.nextLine();String str = sc.nextLine();char[] a = str.toCharArray();int count = 0;for (int i = 0; i < n; i++) {char temp = a[i];if ('1' <= temp && temp <= '9') {//left,right为警察可以监视的范围int left = Math.max(0, i - (temp - '0'));int right = Math.min(i + (temp - '0'), n - 1);for (int x = left; x <= right; x++) {if(a[x]=='X'){//在可监视范围内，遇到小偷就+1，并把小偷转换为普通人，防止之后再多次技术count++;  a[x]='#'; }}}}System.out.println(count);System.out.println(str);}}

package cn.com.jingdong;
import java.util.HashSet;
import java.util.Scanner;public class Main3 {public static void main(String[] args) {Scanner sc = new Scanner(System.in);int n = sc.nextInt();String s = sc.next();HashSet<Integer> set = new HashSet<>();//存放可监视范围内的小偷所在位置索引，用set可以去除重复计数的小偷for (int i = 0; i < n; i++) {if (Character.isDigit(s.charAt(i))) {int k = s.charAt(i) - '0';if (k == 0)continue;int l = Math.max(0, i - k);int r = Math.min(n - 1, i + k);for (int x = l; x <= r; x++) {if (s.charAt(x) == 'X')set.add(x);}}}System.out.println(set.size());}
}